DE10333876A1 - Tensioning element or deflection element for belt drive or cogged-belt drive of internal combustion engine, comprises a spacer made of material with high heat conductivity in thermal contact to the inner ring of the roller bearing - Google Patents

Abstract

The tensioning element comprises a spacer (10) in thermal contact to the inner ring (21) of the roller bearing (8). The spacer is made of material with high heat conductivity, and overlaps the inner ring in the radial direction, in the region of the roller bearing. The spacer may be made of a copper alloy or an aluminum alloy.

Description

The Invention relates to a tensioning element or deflecting element of a traction mechanism drive, especially for an internal combustion engine, with a pulley, by means of a roller bearing is rotatably mounted on a fastening means, wherein the fastening means mounted in a holder of the clamping element or on an engine block is and with a spacer, on which an inner ring of the bearing is arranged and which with its facing away from the inner ring Front side abuts a bracket or the engine block and the Surrounds fastener.

In Motor vehicles are traction drives, for example, as a timing belt drives for driving camshafts, or as V-belt drive for driving Ancillaries such as cooling water pump, Generator or air conditioning compressor known. Important elements of this Traction drives represent the tensioning and deflection. Both Elements are characterized by being a pulley exist, which partially entwined by the belt of the traction drive become. The task of the deflecting element is the minimum wrap To ensure the pulleys, for example, the ancillaries. Clamping elements are used around the belt of the traction drive to maintain a defined constant tension and thus slip of a belt or skipping to avoid a toothed belt. The idle pulleys of the tensioner and deflection elements consist essentially of a pulley, on the belt of the traction drive is guided. The pulley is with the help of a rolling bearing rotatably mounted on a shaft which on the clamping element or the Engine block is attached. With the help of a spacer between Inner ring and attachment point, a defined distance between Rolling bearings / pulley and bracket ensured.

From the DE 100 43 840 A1 is a generic deflecting known. It comprises a roller bearing whose outer ring is enclosed by a ring body made of plastic. The inner ring of the rolling bearing is located on a guide lug of a fastening screw and a spacer. The spacer is connected via projections with the fastening screw.

Furthermore, in DE 100 13 978 A1 a role of a tensioning device of a traction mechanism shown. It consists of a rolling bearing on the outer ring of a pulley in the form of a non-cutting formed sheet metal part is attached. The inner ring of the rolling bearing is in turn connected to a fastening screw and a spacer.

in the Operating condition of the idler pulley occur in the rolling bearing Frictional effects on, for heating of the rolling bearing to lead. Such friction effects are z. B. the rolling friction between rolling elements and Raceway, slip between rolling elements and races, friction between rolling elements and Cage and Cage and Race rings and intermediate pulley and belt in slip. at sealed bearings occurs in addition a friction between the sealing lips and the races on. The Size of this Rei Bungseffekte and thus the heating of the bearing depends on both the load as well as the speed of the rolling bearing.

rotation speed and load the rolling bearings Idling pulleys have always been through the insertion new ancillaries in the accessory operation continuously increased what leads to an increase in the storage temperature. This places high demands on the individual components of the rolling bearing, and, in particular, reduces the grease and seal life, which to a lifetime shortening of the rolling bearing leads. additionally is the heat dissipation through sound shielding measures or compact design of the internal combustion engine adversely affected.

Summary the invention

The Invention should take into account the problems presented and the heat dissipation from the rolling bearing improve the pulley, resulting in improved reliability and longer Lifespan of tensioning and deflecting leads.

According to the invention this Task solved by that the spacer is in thermal contact with the inner ring of the rolling bearing and from a Material with a high thermal conductivity exists. The advantage of this arrangement is that it produces from the warehouse Heat energy fast transferred to the spacer is and in this from the rolling bearing carried away becomes. As a consequence, a heat reservoir forms, the physical Dimensions significantly larger than that of the rolling bearing are alone. Because the final Removal of heat, by effects such as convection, forced convection or radiation, are area-dependent, does this to that of the rolling bearing dissipated Thermal energy more effective and faster discharged from the deflection or tensioning pulley and can be delivered to the environment.

Advantageously surmounted the spacer in the Area of the rolling bearing the inner ring in the radial direction. This will be the rolling bearing effectively protected against dirt and spray.

moreover is on a thermally optimized surface structure to pay attention. Furthermore, it is proposed that the spacer from a Copper alloy exists. Advantageous here is the high thermal conductivity (about 400 W / m K).

Also conceivable is an embodiment in the spacer consists of an aluminum die-cast part. Again, the affects high thermal conductivity of the material (about 150 W / m K) advantageous to the heat transfer from the rolling bearing away.

In a further embodiment of the invention Invention is between the spacer and the inner ring of the bearing a sleeve made of a material with a high thermal conductivity, the Sleeve in the bore of the rolling bearing is attached and the inner surface the inner ring of the rolling bearing at least partially covered. By the insertion a sleeve high thermal conductivity between spacers and inner ring can be the contact surface between heat source (Bearing inner ring) and heat reservoir (Spacer) be increased decisively. this leads to to that the thermal contact resistance decreases, causing heat dissipation favored becomes.

advantageously, is the sleeve produced by chipless forming a sheet metal part. This is done the production cost-effective with the help of a simple work process.

In an advantageous embodiment there is the sleeve from a copper alloy.

advantageously, is the sleeve as an angle sleeve accomplished and the radially extending portion of the spacer is at least partially in contact with the radially extending Part of the angle sleeve. The enlargement of the contact area can be achieved by the axial and radial dimensions the sleeve those of the rolling bearing and of the spacer be adjusted. The contact surface between inner ring and angular sleeve can be influenced by the axial dimensions of the angle sleeve, while the contact area between angle sleeve and spacer be increased by the radial dimension of the annular disc of the angle sleeve can. The rapid heat transport between these two contact surfaces due to the good thermal conductivity of the material.

A another embodiment The invention provides that at least one of the contact surfaces between Inner ring, spacer and sleeve Thermal Compounds is applied. This offers the advantage that the heat conduction not just about the microscopic contact points between spacer and inner ring takes place but that the heat dissipation over the entire contact surface guaranteed is. Another advantage stems from the fact that with the help of Thermal Compounds the effective contact surface between inner ring of the rolling bearing and spacer elevated can be. These two effects can dissipate heat from the inner ring of the rolling bearing drastically increased away become.

In a further advantageous embodiment of the invention the contact surface between inner ring and spacer by applying a thermal compound increased. By the larger contact area is a better heat transfer from Inner ring to the spacer guaranteed.

Farther is provided that the spacer with cooling fins is provided. By this measure becomes the effective surface of the heat reservoir elevated and thus the final one heat dissipation by convection, forced convection or radiation clearly favored.

In Further embodiments of the invention is proposed radial fan blades to attach to the pulley on the side of the spacer that airs the spacer beschaufeln. By this measure will be the final one heat dissipation through increased forced convection favors. It can the radial fan blades as executed separate component be attached to the pulley or the pulley and the radial fan blades be executed in one piece.

A advantageous embodiment The invention provides that the pulley and the radial fan blades executed in one piece and are manufactured by a chipless forming process. It will by a non-cutting forming process, the pulley from a Sheet metal part manufactured and then in the same step from the radially extending portions of the pulley, the radial fan blades shaped. The advantages of this embodiment are simple and cost-effective production the pulley including radial fan blades and the circumstance that no extra Component needed which does not increase the weight of the component and assembly is simplified.

Furthermore, it is proposed that blades are mounted on the side facing away from the spacer end face of the pulley, which establish air flow through the air inlet openings in the pulley to the rolling bearing. In this case, both embodiments are detected, in which the radial fan blades are designed as a separate component, as well as embodiments in which pulley and radial fan blades made in one piece leads are.

Farther There is also the possibility here Pulley with the air inlets and blades in one piece to manufacture from a non-cutting formed sheet metal part.

Short description of drawings

Further Features of the invention will become apparent from the following description and from the drawings, in the embodiments of the invention are shown simplified. Show it:

1 Longitudinal section of a tensioning element of a traction mechanism drive,

2 a first embodiment of a roll of a tensioning or deflecting element in longitudinal section,

3 a second embodiment of a roll of a tensioning or deflecting element in longitudinal section,

4 A third embodiment of a roller of a tensioning or deflecting element in a 3-D representation,

5 A fourth embodiment of a roller of a tensioning or deflecting element in a 3-D representation,

6 a fifth embodiment of a roller of a tensioning or deflecting element in longitudinal section,

Full Description of the drawings

In 1 is a tensioning element 1 shown in a longitudinal section. It consists of a stationary housing 2 , on whose trunnion 3 a hub 4 is arranged pivotally. At one end of the hub 4 closes a tension arm 5 on, the end with a role 6 is provided. The role 6 consists of a pulley 7 that have a rolling bearing 8th rotatable with a fastener 9 connected is. In addition, the rolling bearing is located 8th on a spacer 10 on. About a spring means 11 can the role 6 of the clamping element 1 be biased against a belt R.

In the following, the invention is based on roles 6 of deflecting elements 12 being represented. Of course, these roles of the invention 6 also in clamping elements 1 Find use. 2 shows an inventive embodiment of a deflecting element 12 , Shown is a pulley 7 , consisting of a non-cutting formed sheet metal part, via a rolling bearing 8th on a fastener 9 is rotatably mounted. The fastener 9 consists of a threaded section 13 a shaft 14 , a Führungsan sentence 15 and a head 16 , The pulley 7 consists of an axially extending longer section 17 and an axially extending shorter portion 18 together, with both sections 17 . 18 through a connector 19 are connected. An unillustrated traction means is on the outer surface of the longer section 17 guided. The radially inner lateral surface of the shorter section 18 is non-rotatable with the outer surface of the outer ring 20 of the rolling bearing 8th connected. Both positive and positive and cohesive connections are conceivable. The inner ring 21 of the rolling bearing 8th is through the leadership approach 15 of the fastener 9 centered. In addition is a spacer 10 mounted so that the inner ring 21 of the rolling bearing 8th also centered on this. Both the head 15 of the fastener 9 as well as the spacer 10 cover the inner ring 21 of the rolling bearing 8th in the radial direction and secure the rolling bearing 8th by targeted bias against loosening. During operation of the clamping element 1 or the deflecting element 12 is due to various friction mechanisms in the rolling bearing 8th Generates heat that significantly reduces the Dichtscheiben- (elastomers) and grease life and thus the life of the bearing with insufficient cooling. The heat dissipation takes place mainly via the contact surfaces between the outer ring 20 with the pulley 7 and inner ring 21 with the leadership approach 15 and the spacer 10 , Three factors play a key role here. First, the heat transfer through the contact surface to the heat reservoir must be maximized, second, it is necessary that the amount of heat transferred quickly from the bearing 8th Thirdly, the dissipated heat energy must be released quickly to the environment. The heat transfer across the contact surface depends on two factors, the macroscopic and the microscopic contact surface. The macroscopic contact surface can be easily replaced by a larger overlap between inner ring 21 and spacer 10 be achieved. For this purpose is between the inner ring 21 of the rolling bearing 8th and the spacer 10 in the present embodiment, an angular sleeve 22 appropriate. The angular sleeve 22 covers the inner ring 21 on a larger area than the spacer 10 and thereby significantly improves the Wärmeleitkontaktwiderstand. Furthermore, the angular sleeve 22 so out leads that the contact surface between angle sleeve 22 and spacer 10 is significantly larger than in the case without angled sleeve 22 the case would be. The angular sleeve 22 is advantageously designed so that it covers a large area of the inner circumferential surface of the inner ring 21 and its forehead covered. In the radial direction outside of the inner ring 21 is the angle sleeve 22 in the axial direction of the rolling bearing 8th offset, whereby the radial extent of the angular sleeve 22 can be increased without additional friction between angle sleeve 22 and rolling bearings 8th arises. At the same time thereby the contact surface to the spacer 10 be enlarged, as this also extends further in the radial direction outwards and in contact with the angular sleeve 22 stands.

To the heat conduction within the angular sleeve 22 and inside the spacer 10 it is proposed to increase the angular sleeve 22 made of a copper alloy whose thermal conductivity is about 400 W / m K and the spacer 10 also made of a copper alloy or an aluminum die cast alloy. The thermal conductivity of the aluminum die cast alloy is between 150 W / m K and 160 W / m K.

By inserting the angle sleeve 22 can the contact surface between inner ring 21 and spacer 10 significantly increased and thus the heat flow from the inner ring 21 be significantly improved. The use of highly thermally conductive materials in the design of the angle sleeve 22 and / or the spacer 10 improves the heat flow from the inner ring 21 away within these components, which leads to a significantly better cooling of the bearings. Due to the longer axial configuration of the spacer 10 There is a large area available around the rolling bearing 8th indicate heat energy directed to the environment. This can be done through mechanisms such as convection, forced convection and radiation. The efficiency of these mechanisms depends to a large extent on the size of the surface of the heat reservoir. By enlarging the surface of the component to be cooled, of course, the final heat dissipation is clearly facilitated. The angle sleeve can additionally serve as a non-positive element or transport lock.

3 shows a further embodiment of a roller according to the invention 6 a tensioning element 1 or a deflecting element 12 , A pulley 7 is about a rolling bearing 8th rotatable on a fastener 9 arranged. pulley 7 and outer ring 20 of the rolling bearing 8th are rotatably connected. Furthermore, the inner ring 21 of the rolling bearing 8th also rotatably with the fastener 9 connected, with the rolling bearing 8th in the radial direction on the guide lug 15 of the fastener 9 supported. Furthermore, a spacer 10 shown on which the inner ring 21 centered. Against loosening is the inner ring 21 through the head 16 and through the spacer 10 secured. In the present embodiment, the inner ring is located 21 directly on the spacer 10 on. To increase the contact area became the cavity 24 with thermal grease 25 filled, causing the macroscopic contact surface and thus the thermal conductivity between the inner ring 21 and spacer 10 is increased. Furthermore, it is conceivable, the contact surface between spacers 10 and inner ring 21 by applying thermal compound 25 between the two components in the microscopic area to improve. The spacer 10 is in turn made of a material of high thermal conductivity, primarily a copper alloy or an aluminum die-cast alloy. The on the inner ring 21 of the rolling bearing 8th stored heat energy can now faster through the enlarged contact surface in the spacer 10 and due to the advantageous choice of material in the spacer 10 faster from the rolling bearing 8th be carried away. By enlarging the microscopic and macroscopic contact surfaces inner ring 21 and spacer 10 a better heat transfer and thus a lowering of the storage temperature is achieved. The distribution of heat energy to the rolling bearing 8th and the spacer 10 increases the effective cooling surface and thus in turn improves the ultimate dissipation of heat energy to the environment.

4 shows a further advantageous embodiment of the invention. The role 6 is almost identical to those in 2 or 3 why the same reference numbers are used. Clearly visible is the pulley 7 , the spacer 10 and the fastener 9 , The only difference to the previous embodiments are in the radially extending section 23 the pulley 7 attached radial fan blades 26 , In the illustrated embodiment, the radial fan blades are 26 and the pulley 7 formed in one piece. However, it is also quite possible, the radial fan blades 26 extra to manufacture and attach to the pulley 7 to fix. Task of the radial fan blades 26 it is the air circulation at the spacer 10 increase and accelerate the release of heat energy to the environment.

The radial fan blades 26 are preferably made analogous to those of air-cooled generators (blades asymmetric).

It is proposed the radial fan blades 26 from the material of the radial section 23 the pulley 7 to shape. For this purpose, different areas of the pulley 7 punched, creating a tab 27 is defined. The punching defines areas where the tab is 27 no material connection with the rest of the pulley 7 having. Then the tab 27 from the pulley 7 in the axial direction to the distance piece 10 bent. The radial fan blades thus produced 26 can box-low and with little effort during the molding process of the pulley 7 getting produced. The axes 28 to the the tabs 27 can be bent in the axial direction, radially inward, to the axis of rotation 31 the role 6 , run or any angle of attack 32 show less than 90 °. For noise optimization, it is intended for the radial fan blades 26 a pulley 7 different angles of attack 32 to realize, whereby resonance effects can be avoided and the noise pollution decreases.

In conjunction with the features of the embodiments 2 or 3 This results in an effective mechanism for cooling a rolling bearing 8th , The enlarged contact surface between rolling bearings 8th and spacer 10 and the choice of material for the spacer 10 with a high thermal conductivity allows effective heat energy dissipation from the bearing 8th to the spacer 10 in the area of the radial fan blades 26 is effectively cooled.

5 and shows a further embodiment of the invention. Shown again is the role 6 a deflecting element 12 , The embodiment is almost identical to that in FIG 2 why the same reference numbers have been used for the same parts. It is conceivable, of course, an embodiment almost identical to that of 3 , In addition to their features are here in the pulley 7 Air inlet openings 29 formed a direct airflow 35 to the rolling bearing 8th establish. In the present example, the air inlet openings 29 with shovels 30 provided during operation of the deflecting element 12 increase the air circulation from outside to inside. The air flow from the inside of the ball bearing to the outside. The shovels 30 are in the present example in one piece with the pulley 7 educated. However, it is also possible the blades 30 as a separate component and this on the pulley 7 to fix. In operation of the pulley 7 is now cooling air with the help of the blades 30 through the air inlet openings 29 to the rolling bearing 8th steered, whereby an effective cooling of the rolling bearing 8th can take place. The shovels 30 can by punching the pulleys 7 and subsequent bending out can be made inexpensively and with little manufacturing effort. Another advantage of this embodiment is that no new components have to be added by the one-piece embodiment and thus no weight penalty arises.

In 6 is shown a further embodiment, which is largely consistent with the embodiment 5 is identical, which is why the same reference numerals are used. In addition to the features of the embodiment 5 are on the spacer ( 10 ) Cooling fins ( 34 ) is attached to the surface of the spacer ( 10 ) and thus improve the heat dissipation.

Although only roles 6 with pulleys 7 consisting of a Blechumformteil shown, the invention of course also relates to other embodiments, such as pulleys made of plastic.

Conceivable, of course, are combinations of different features of different embodiments. For example, the combination of radial fan blades ( 26 ) with cooling fins ( 34 ) on the spacer ( 10 ).

1

clamping element

2

casing

3

pivot

4

hub

5

clamping arm

6

role

7

pulley

8th

roller bearing

9

fastener

10

spacer

11

spring means

12

deflecting

13

threaded portion

14

shaft

15

leadership approach

16

head

17

longer section

18

shorter section

19

joint

20

outer ring

21

inner ring

22

angle sleeve

23

radial section

24

cavity

25

Thermal Compounds

26

Radial fan blades

27

flap

28

axis

29

Air inlet openings

30

shovel

31

axis of rotation

32

angle of attack

33

shell

34

cooling fins

35

airflow

Claims (17)

Clamping element ( 1 ) or deflection element ( 2 ) a belt or toothed belt drive, in particular for an internal combustion engine, with a pulley ( 7 ), which by means of a rolling bearing ( 8th ) rotatably mounted on a fastening means ( 9 ) is mounted, wherein the fastening means ( 9 ) in a holder of the clamping element ( 1 ) or attached to an engine block, and with a spacer ( 10 ) on which an inner ring ( 21 ) of the rolling bearing ( 8th ) is arranged and which abuts with its facing away from the inner ring end face on a bracket or on the engine block and the fastening means ( 9 ), characterized in that the spacer ( 10 ) in thermal contact with the inner ring ( 21 ) of the rolling bearing ( 8th ) and consists of a material with a high thermal conductivity. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that the spacer ( 10 ) in the area of the rolling bearing ( 8th ) the inner ring ( 21 ) projects in the radial direction. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that the spacer ( 10 ) consists of a copper alloy. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that the spacer ( 10 ) consists of a Aluminiumdruckgußteil. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that between spacer ( 10 ) and inner ring ( 21 ) of the rolling bearing ( 8th ) a sleeve ( 33 ) is made of a material with a high thermal conductivity, wherein the sleeve ( 33 ) in the bore of the rolling bearing ( 8th ) and the inner surface of the inner ring ( 21 ) of the rolling bearing ( 8th ) at least partially covered. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 5, characterized in that the sleeve ( 33 ) is produced by chipless forming a sheet metal part. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 5, characterized in that the sleeve ( 33 ) consists of a copper alloy. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 5, characterized in that the sleeve ( 33 ) as an angle sleeve ( 22 ) is executed and that the radially extending portion ( 23 ) of the spacer ( 10 ) at least partially in contact with the radially extending portion of the angular sleeve ( 22 ) stands. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1 or 5, characterized in that at least one of the contact surfaces between the inner ring ( 21 ), Spacer ( 10 ) and sleeve ( 32 ) Thermal grease ( 25 ) is applied. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that the surface Kontaktflä between inner ring ( 21 ) and spacer ( 10 ) by applying a thermal compound ( 25 ) is increased. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that the spacer with cooling ribs ( 34 ) is provided. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that radial fan blades ( 26 ) on the pulley ( 7 ) on the side of the spacer ( 10 ), which are the spacer ( 10 ) with air. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 12, characterized in that the radial fan blades ( 26 ) are designed as a separate component and this on the pulley ( 7 ) are attached. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 12, characterized in that the pulley ( 7 ) and the radial fan blades ( 26 ) are made in one piece. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 14, characterized in that the pulley and the radial fan blades are made in one piece and manufactured by a chipless forming process. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 1, characterized in that on the of the spacer ( 10 ) facing away from the pulley ( 7 ) Paddles ( 30 ), which pass through air inlets ( 29 ) in the pulley ( 7 ) an airflow ( 35 ) to the rolling bearing ( 8th ) establish. Clamping element ( 1 ) or deflection element ( 2 ) of a belt or toothed belt drive according to claim 15, characterized in that the pulley ( 7 ) with the air inlet openings ( 29 ) and the blades ( 30 ) in one piece from a spanlos formed sheet metal part are made.